Hitherto, as this kind of fluid pressure cylinder apparatus having a throttle valve, an apparatus in which a moving speed of a piston is controlled by adjusting a flow of pressurized fluid supplied to or discharged from a pressure chamber with a throttle valve, an apparatus in which the piston is stopped at an end of stroke in a buffered manner by means of limiting a flow of fluid discharged from a pressure chamber with a throttle valve when the piston approaches the end of the stroke, or the like is known.
In such a cylinder apparatus, generally, as the throttle valve, a variable throttle valve configured to adjust a square measure of an opening of an orifice by advancing and retreating a cone-shaped valve rod is used and the variable throttle valve is attached to a cylinder body.
In FIG. 9, a main part of the conventional fluid pressure cylinder apparatus provided with such a variable throttle valve 50 is illustrated. This cylinder apparatus includes a cushion chamber 56 other than a pressure chamber 52 in an inner part of a cylinder body 51, in which the cushion chamber 56 is interrupted from the pressure chamber 52 by means of a collaborative action of a rod 54 and a sealing member 55 when the piston 53 approaches the end of the stroke, whereas the cushion chamber 56 is allowed to communicate with the pressure chamber 52 when the piston 53 is in the middle of the stroke, and a port (not shown) is formed so as to be allowed to communicate with the cushion chamber 56. In addition, after the cushion chamber 56 is interrupted from the pressure chamber 52, the fluid in the pressure chamber 52 flows into the cushion chamber 56 via a through-hole 58b from a through-hole 58a, while receiving a limit of flow by the throttle valve 50, and is discharged from the port. Thereby, the piston 53 is configured to be stopped at the end of the stroke in the buffered manner.
The throttle valve 50 is constructed such that a valve holder 60 is attached to a valve hole 59 formed in the cylinder body 51, and a valve rod 61 provided with a cone-shaped adjusting portion 61a at a tip end thereof is movably mounted in the valve holder 60 in an advancing and retreating manner in a direction of an axis line of the valve hole 59 upon rotating operation. In addition, at a base end portion 61b where a male screw of the valve rod 61 is provided, a lock nut 63 for preventing the valve rod 61 from being rotated by vibration or the like after the square measure of the opening is adjusted is attached.
In the conventional fluid pressure cylinder apparatus, the throttle valve attached to the cylinder body is configured to adjust the square measure of the opening of the orifice by means of advancing and retreating the valve rod in the direction of the axis line. Accordingly, a dimension of the valve rod in a direction along the axis line is large, and in addition, an operating area for advancing and retreating the valve rod has to be secured. Consequently, there has been a large limitation on downsizing.
Further, there has also been a problem that when the valve rod, the valve holder, the lock nut, or the like is widely protruding outward of the cylinder body, it tends to be impeditive for treating the cylinder, or for attaching other devices in the vicinity of the cylinder.